British pharmacologist John H. Gaddum worked under Henry Dale at the National Institute for Medical Research, and helped develop the classical laws of drug antagonism. He showed that sympathetic nerves release adrenaline, and in collaboration with Ulf von Euler established the release of acetylcholine in autonomic ganglia. In experiments with lysergic acid diethylamide (LSD), Gaddum explained how it causes mental disturbances by blocking serotinin's stimulation effects. He also authored an advanced pharmacology text which was considered definitive for decades.